Development of photographic silver halide material

ABSTRACT

A method is described of producing high-contrast images by exposure and development of a photographic lith-type silver halide material wherein the lith material incorporates hydroquinone and development occurs by treating the exposed material with an alkaline development activator in the presence of hydroxylamine or a N-mono-substituted hydroxylamine. Processing time is reduced and the processing composition can be used for extended periods of time without replenishment. Favourable dot quality can be obtained.

United States Patent Hofman et al.

DEVELOPMENT OF PHOTOGRAPI-IIC SILVER HALIDE MATERIAL Inventors: EmielAlexander Hofman, Mortsel;

Leo Pierre De Bie, Kontich; Jules Robert Berendsen, Deurne, all ofBelgium Assignee: AGFA-Gevaert, Mortsel, Belgium Filed: May 18, 1973Appl. No.: 361,576

Foreign Application Priority Data May 26, 1972 Great Britain 25068/72U.S. Cl 96/95, 96/66 R, 96/66.3 Int. Cl G03c 1/06, G03c 5/30 Field ofSearch 96/66 R, 66.3, 95, 76 R References Cited UNITED STATES PATENTS3,128,180 4/1964 Henn r. 96/95 3,518,085 6/1970 Milton et al. 96/66.33,615,529 10/1971 Tajima et al 96/95 OTHER PUBLICATIONS Photo Sci. Eng.Vol. 17, No. 3, May/June 1973, pp. 255-260, Willems.

Primary ExaminerMary J. Kelley Attorney, Agent, or Firm-A. W. Breincr[57] ABSTRACT A method is described of producing high-contrast images byexposure and development of a photographic lith-type silver halidematerial wherein the lith material incorporates hydroquinone anddevelopment occurs by treating the exposed material with an alkalinedevelopment activator in the presence of hydroxylamine or aN-mono-substituted hydroxylamine. Processing time is reduced and theprocessing composition can be used for extended periods of time withoutreplenishment Favourable dot quality can be obtained.

23 Claims, No Drawings DEVELOPMENT OF PHOTOGRAPHIC SILVER HALIDEMATERIAL The present invention relates to processing of exposedhigh-contrast silver halide materials for graphic arts use andparticularly to processing of photographic silver halide materials ofthe lith type wherein the hydroquinone developing agent is incorporatedinto the said material.

In the photomechanical arts photographic films capable of providing highimage contrast are required for the preparation of the line andhalftonefilm intermediates, which are used in making printing plates. Inreproducing continuous tone material, it is customary to make a halftonephotographic intermediate, usually a film negative, in which thegradations in tone are represented by differing sizes of dots of uniformdensity. The shape, density and uniformity of the halftone dots areclosely correlated to the quality of the resulting picture.

Lith-type emulsions are high-contrast fine-grain silver halide emulsionscontaining at least about 50 mole percent of silver chloride and atleast about 5 mole percent of silver bromide. If desired they maycomprise up to about 5 mole percent of silver iodide but generally theiodide content is less than about 1 mole percent. They have acharacteristic curve with short toe and high-gamma and produce sharplydefined images with high density extending to. the edges of lines anddots. This applies especially when a developer with so-calledlith-effect is used. Up till now these lith-type developers comprisehydroquinone as the sole developing agent and have a very' low sulphiteion content, which is maintained at a low and constant value by theaddition to the sulphite containing developing solution of formalin(paraformaldehyde) or by the direct addition to the solution of theaddition product of sulphite and formalin namely sodium formaldehydehydrogen sulphite. The mechanism of operation of these lith-typedevelopers has been described by J. A. C. Yule in the J. Franklin Inst.,239 (l945), P. 221-230.

Ordinary lith-developers with low free sulphite content have thedisadvantage of short life in storage and use because they tend tooxidize very rapidly; therefore, they must often be replaced orreplenished.

Before use such developer solutions must be stored in two parts sincethe sodium formaldehyde hydrogen sulphite dissociates in the alkalinemedium of the developer to form the sulphite ion as well as an equimolaramount of formaldehyde, which reacts with hydroquinone and destroys itsdeveloping power.

When used in continuous transport processing machines the commonly knownlith-type developers for high-contrast films give rise to results ofinferior quality as compared with careful tray processing as a result oflocally varying concentration of the developing agent and its exhaustionproducts.

It is known for the development of silver halide material to incorporateone or more silver halide developing agents into the material itself andto effect development after exposure by treatment of the material withalkaline compositions substantially free of developing agents and calleddevelopment activators. In this way the processing composition can bestored-for a very long time, it does not become exhaustedso easily andit need not be replenished.

Experiments which were carried out to extend these advantages to theprocessing of lith-material, by incorporating the sole developing agenthydroquinone into the lith-material and effecting development by meansof an alkaline activator comprising sodium formaldehyde hydrogensulphite, were not successful in that development was incomplete and thedensity of dots was unacceptable.

Accordingly itis an object of the present invention to provide alith-type system wherein the hydroquinone developing agent is present inthe lith-material and lithdevelopment is effected by means of analkaline activator substantially free of hydroquinone developing agent.

It is a further object of the present invention to re-. duce developmenttime of photographic silver halide elements of the lith-type yieldinghigh-contrast and favourable dot-quality.

Another object of the present invention is to provide a processingcomposition for lithtype silver halide ele-, ments that is less liableto exhaustion and can be used for extended periods of time withoutreplenishment.

It is also an object of the present invention to keep, duringdevelopment, the concentration of hydroquinone locally constant, whichis of particular value for automatic machine-processing.

The above objects and other objects, which will be apparent from thefurther disclosures, have been accomplished by incorporating thehydroquinone developing agent into the lith-type photographicsilverhalide material and effecting development by means of an alkalinedevelopment activator in the presence of hy-. droxylamine or aN-monosubstituted hydroxylamine derivative. If so desired, two or moreof said hydroxylamines may be used.

Particularly suitable hydroxylamines for use accord;- ing to the presentinvention. can be represented by the formula:

wherein R represents hydrogen, alkyl, e.g., methyl, ethyl, propyl,isopropyl, octyl, decyl, dodecyl, etc. in.-

cluding substituted alkyl e.g., alkyl substitutedibyanyl such as phenyl,hydroxy, carboxyl, sulpho, amino, sub.- stituted amino, and NHOH, oraryl including substituted aryl e.g., aryl substituted. by. halogen,alkyl; alkoxy, hydroxy, carboxyl, sulpho, alkoxycarbonyl, amino andsubstituted amino.

It will be understood that acid. addition salts of the hydroxylaminecompoundsmay also be used in thisinvention which include, for.example,,sulphates, phosphates, carbonates, oxalates, acetates.andzchlorides. 0f

' course, the acid salt usedshould have no detrimental effect on thephotographic material.

Representative examples of hydroxylamine compounds for use according tothe present invention are. hydroxylamine, N-methylhydroxylamine,N-ethylhydroxylamine, N-propylhydroxylamine,N-ysulphopropylhydroxylamine, N-a-carboxypropylhydroxylamine,N-isopropylhydroxylamine, N-pheny-lhydroxylamine,a-hydroxylaminovfifphenyl propionic acid, Np-carboxyphenylhydrox-ylamine, N-pmethoxy-phenylhydroxylamine,N-mssulphophenylhydroxylamine, and

Z aorza-ca-cn -o-anon neon which can be prepared as described in Ber.40, 218.

The present invention thus provides a method of pro: ducinghigh-contrast images by exposure and development of a photographiclith-type silver halide material, wherein said lith-type materialincorporates hydroquinone as developing agent and development iseffected by treatment of the exposed material with an alkalinedevelopment activator in the presence of hydroxylamine or aN-mono-substituted hydroxylamine.

As already noted above a lith-type silver halide material comprises asilver halide emulsion layer containing at least about 50 mole percent,preferably at least about 70 mole percent of silver chloride, at leastabout 5 mole percent of silver bromide and from to about mole percent ofsilver iodide. The average grain diameter is preferably comprisedbetween about 0.1 and about 0.4 micron.

The hydroxylamine compound may be present in the alkaline solution or inthe photographic lith-type material or in both. Therefore, the presentinvention also provides a photographic silver halide material as definedabove containing hydroquinone which comprises in the said silver halideemulsion layer and/or in a hydrophilic colloid layer in water-permeablerelationship therewith hydroxylamine or a N-monosubstitutedhydroxylamine. In the lith-type silver halide material used inaccordance with the present invention, the hydroquinone developing agentshould be in effective contact or relationship with the silver halide,which means that it should be present in the silver halide emulsionlayer itself and/or in one or more other hydrophilic colloid layers inwater-permeable relationship with the silver halide emulsion layer e.g.,a hydrophilic colloid intermediate layer arranged between the supportand the silver halide emulsion layer or a hydrophilic colloid layercoated over the silver halide emulsion layer.

The alkaline development activator is normally free of hydroquinonedeveloping agent. However, when the processing medium is used repeatedlyfor processing successive elements it may comprise after some time aminor amount of hydroquinone, which has diffused from the element intothe processing medium.

According to a preferred embodiment of the present invention, ahydrophilic colloid intermediate layer e.g., a gelatin layer is arrangedbetween the support and the light-sensitive silver halide emulsion layerof the lithmaterial.

Such hydrophilic colloid intermediate layer has a weight preferablycomprised between about 2 and about g of hydrophilic colloid, moreparticularly gelatin, per sq.m.

The hydroquinone is preferably incorporated in .such hydrophilic colloidlayerarranged between the support and the emulsion layer and/or in ahydrophilic colloid layer coated over the emulsion layer, e. g., agelatin protective surface coating. V

The hydroquinone developing agent is incorporated into thelith-mate'rialin anamount preferably comprised between about 5 and aboutmmol per sq.m.

The hydroxylamine compounds may be used in widely varying amounts.Dependent on the particular compound involved they are used preferablyin an amount comprised between about 0.5 g and about 50 g per litre ofalkaline development activator. When used in the photographic elementitself they are preferably used in amounts between about 50 mg and about1 g per sq.m.

The silver halides are dispersed in hydrophilic colloid materials usedas binders which include gelatin, collodion, gum arabic, casein, zein,cellulose ester derivatives such as alkyl esters of carboxylatedcellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose,alginic acid, polyvinyl alcohol and other synthetic resins well known inthe art. Gelatin is preferably used as hydrophilic colloid binder. Thebinding agents for the emulsion layer may also contain dispersedpolymerized vinyl compounds. Such compounds are disclosed e.g., in theUS. Pat. Nos. 3,142,568 of Robert William Nottorf issued July 28, 1964,3,193,386 of Clayton F. A. White issued July 6, 1965, 3,062,674 ofRobert Wong issued Nov. 6, 1962, 3,220,844 of Robert C. Houck, Donald A.Smith and Joseph S. Yudelson issued Nov. 30, 1965 and 3,518,085 of KirbyM. Milton and Charles A. Goffe issued June 30, 1970. They include thewater-insoluble polymers of alkyl acrylates and methacrylates, acrylicacid, sulfoalkyl acrylates or methacrylates, interpolymers of alkylacrylates with acrylic acids, acryloyloxyalkylsulphonic acids,acetoacetoxyalkyl acrylates such as 2- acetoacetoxyethyl methacrylateand the like. These compounds may be incorporated likewise into aseparate layer of the photographic element. The vinyl polymers may beemployed in concentrations of about 20 to about 80 percent, most oftenconcentrations of at least 50 percent by weight, based on the weight ofthe binding agent.

Silver halide emulsions wherein the binding agent contains a dispersedpolymerised vinyl compound provide particularly good results ineliminating drag streaks and dot distortions.

Thev silver halide emulsions may be chemically sensitized by effectingthe ripening in the presence of 'small amounts of sulphur-containingcompounds such as allyl thiocyanate, ally] thiourea, sodiumthiosulphate, etc. The emulsions may also be sensitized by means ofreductors for instance tin compounds as described in United KingdomPatent Specification No. 789,823 filed Apr. 29, 1955 by GevaertPhoto-Producten NV. and small amounts of noble metal compounds such asgold, platinum, palladium, iridium, ruthenium and rhodium compounds.

The emulsions may be used without being spectrally sensitized; however,it is advantageous to spectrally sensitize them according to methodswell known in the art to make them ortho-sensitized or panchromaticallysensitized. Spectral sensitizers that can be used are e.g., thecyanines, merocyanines, complex (trinuclear) cyanines, complex(trinuclear) merocyanines, styryl dyes, oxonol dyes and the like. Suchlike spectrally sensitizing dyes have been described by F. M. Hamer inThe Cyanine dyes and relates compounds (1964).

The silver halide emulsion layer and/or other hydrophilic colloid layersof the high-contrast photographic elements, according to the presentinvention, can also contain conventional addenda for example,plasticizers, coating aids, antistaining agents, fog-inhibitingcompounds and emulsion stabilizers e.g., the azaindenes, such as5-methyl-7-hydroxy-s-triazolo[1,5- a]pyrimidine, and hardeners such asaldehyde hardeners, e.g., formaldehyde, mucochloric acid, glutaraldehydebis(sodium hydrogen sulphite), maleic dialdehyde, aziridines, dioxanderivatives, and oxypolysac charides, as well as hardening agentprecursor compounds which set free the effective hardener only inalkaline medium.

In the lith-type system of the present invention it is preferred to usepolyoxyalkylene compounds, which may be present either in thelith-material or in the development activator or in both. Thesepolyoxyalkylene compounds are widely known for use in lith-materialsand/or lith developers and include any polymeric compound comprising apolyalkylene oxide chain e.g., polyethylene glycol, preferably having amolecular weight of 1500 or more and other ethylene oxide compounds asdescribed amongst others in the United Kingdom Patent Specification Nos.600,058 filed Jan. 10, 1946 by E. I. du Pont de Nemours, 871,801 filedNov. 30, 1956 by Kodak Ltd., 920,637 filed May 7, 1959, 940,051 filedNov. 1, 1961, 945,340 filed. Oct. 23, 1961, 949,643 filed Nov. 2, 1961all by Gevaert Photo-Producten N.V., 991,608 filed June 14, 1961 byKodak Ltd., 1,015,023 filed Dec. 24, 1962, 1,091,705 filed May 20, 1965both by Gevaert Photo-Producten N.V. 1,107,022 filed Oct. 7, 1965,1,147,817 filed Aug. 19, 1966, 1,162,135 filed Oct. 11, 1965, 1,184,434filed Aug. 30, 1966 all byGevaert-Agfa N.V. in FrenchPatentSpecification No. 1,416,850 filed Dec. 8, 1964 by Kodak Ltd., inthe published German Patent Application Nos. 1,141,531 filed Jan. 24,1962 by Perutz Photowerke GmbH, 1,188,439 filed May 16, 1964 by FujiShashin Film Kabushiki Kaisha, and in the U.S. Pat. Nos. 1,970,578 ofConrad Schoeller and Max Wittner issued Aug. 21, 1934, 2,240,472 ofDonald R. Swan issued Apr. 29, 1941 2,423,549 of Ralph Kingsley Blake,William Alexander Stanton and Ferdinand Schulze issued July 8, 1947,2,441,389 of Ralph Kingsley Blake, issued May 11, 1948 and 3,518,085 ofKirby M. Milton and Charles A. Goffe issued June 30, 1970.

The polyethylene oxide compounds may be present in the developmentactivator in an amount ranging from about 0.1 g to about 1 g per litre.When used in the lith-material either in the silver. halide emulsionlayer or an adjacent water-permeable insensitive layer they arepreferably used in amounts ranging from about 0.010 g to about 1 g permole of silver halide.

1n the lith-type system of the present invention, it is also possible touse in addition to the polyoxyalkylene 1 compound aN-vinyl-Z-pyrrolidone polymer or copolymer including addition complexesthereof with iodine as described in British Pat. No. 1,197,306 filedSept. 19, 1966 by Agfa-Gevaert N.V. These N-vinyl-2- pyrrolidonepolymers or copolymers may be used in the silver halide emulsion layeror in another hydrophilic colloid layer in water-permeable relationshipwith the emulsion layer as well as in the alkaline developmentactivator.

As is known to those skilled in the art it may further be advantageousto use in the lith-material or processing solution therefor onium orpolyonium compounds, preferably of the ammonium, phosphonium andsulphonium type or mixtures thereof. Specific onium compounds are e.g.,dodecyl-trimethylammonium ptoluene sulphonate, nonyl pyridiniumperchlorate,

mide, lauryl triethyl phosphonium bromide, onium salts.-

of polyoxyalkylenes e.g., polyoxyalkylene bispyridinium salts forexample 1,1 '-[ethylenetris(oxyethylene) ]bis(pyridinium-p-tolusulphonate) etc. Further examples of suitable oniumcompounds can be found in U.S. Pat. Nos. 2,271,622 of BurtH. Carroll andCharles F. H. Allen issued Feb. 3, 1942, 2,271,623 of Burt H. Carrollissued Feb. 3, 1942, 2,275,727 of Burt H. Carroll and Charles F. H.Allen issued Mar. 10, 1942, 2,288,226 of Burt 11. Carroll and. CharlesF. H. Allen issued June 30, 1942, 2,944,898 of Dorothy J. Beavers,Charles V. Wilson and James L. Graham issued July 12, 1960, 2,944,900 ofBurt H. Carroll, Hubert S. Elins, James L. Graham and Charles V. Wilsonissued July 12, 1960 and 2,944,902 of Burt H. Carroll, John Sagal Jr.and Dorothy J. Beavers issued July 12, 1960.

The silver halide lith-emulsions of use according to the invention maybe coated on a wide variety of sup-, ports. Typical supports arecellulose nitrate film, cellulose ester film, polyvinyl acetal film,polystyrene film, poly(ethy1ene terephthalate) film, and related filmsof resinous materials, as well as glass, paper, metal and the like.Supports such as paper, which are coated with a-olefin polymers,particularly polymers of a-olefins containing two or more carbon atoms,as exemplified by polyethylene polypropylene, ethylene-butylenecopolymers and the like can also be employed.

The lith-material may comprise all conventional layers used in silverhalide elements e.g., subbing layers, filter layers, U.V.-absorbinglayers, antistatic layers, protective surface coatings, etc.

The alkaline composition for effecting development of the exposedlith-material may comprise all kinds of ingredients as commonly employedin lith-type developers, for example thickening agents e.g.,carboxymethylcellulose, compounds releasing halide ions e.g., potassiumbromide, polyoxyalkylene compounds, N-vinyl-2-pyrrolidone polymers andcopolymers, and onium compounds as referred to above, preservativese.g., potassium metabisulphite, sodium formaldehyde hydrogen sulphite,and triethanolamine sulphite, watersoftening agents e.g., polyphosphatesand derivatives of ethylenediamine, tetraacetic acid, wetting agents,etc. Preservatives for developing agents may also be incorporated intothe hydroquinone-containing lith material. The processing solution maycomprise low as well as high sulphite content since the hydroquinonedeveloping agent is present in the silver halide element. The pH of thealkaline processing solution is generally at least about pH 9,preferably at least about pH 1 1.

After the development in accordance with the present invention thedeveloped material may be fixed in the usual way e.g., by means of awater-soluble thiosulphate and then washed, or it may be treated with astabilizing solution comprising an agent capable of convertingnon-exposed'silver halide in substantially lightinsensitive complexes,which need not be removed by washing, e.g., potassium and ammoniumthiocyanate. Alternatively the developed material may be treated with astabilizing and a fixing solution as described in U.S. Pat. No.3,637,389 of Emiel A. Hofman issued Jan. 25, 1972.

Processing of the exposed photographic element can occur in an automaticapparatus wherein the exposed material is transported at a substantiallyconstant speed through the processing stations. If desired, the exposurestation may be coupled to the processing stations of the automaticapparatus.

A suitable automatic processing apparatus according to which the exposedelement is transported through a development activating station, astabilizing station, a fixing station and a rinsing station has beendescribed in French Patent Specification No. 2,107,144 filed Sept. 1,l97l by Agfa-Gevaert N.V.

The following examples illustrate the present invention.

EXAMPLE 1.

A polyethylene terephthalate support was provided with a gelatin layercomprising hydroquinone in a ratio of 8 g of gelatin and 1.77 g ofhydroquinone per sq.m. The gelatin layer was overcoated with a gelatinosilver chlorobromoiodide emulsion (88.7 mole percent of chloride, 1 1mole percent of bromide and 0.3 mole percent ofiodide) in such a waythat per sq.m. an amount of silver halide corresponding to 6 g of silvernitrate waspresent. The silver halide emulsion layer was then overcoatedwith a gelatin antistress layer in a ratio of 0.3 g of gelatin per sq.m.

The light-sensitive material formed was divided into several aliquotstrips. Under identical circumstances each strip was exposed through astep wedge with constant 0.15 and treated at 25C for increasing times inone of the following development activating compositions A, B and C:

COMPOSITION A anhydrous sodium carbonate potassium bromide l g water tomake 1 sodium hydroxide to adjust pH to 12 COMPOSlTlON B Same as A butcomprising in addition g of hydroxylamine sulphate.

COMPOSlTlON C Same as A but comprising in addition g of hydroxylaminesulphate.

8 The developed strips were then fixed, washed and dried in the usualway.

The results attained are listed in the following table.

Table Development Development Fog Gradient in toe amma activating time(sec) 10 solution A l5 0.04 2.52 3.15 30 0.04 2.77 2.l6 0.04 6.32 4.88 B15 30 0.04 9.30 5.60 C 15 0.05 8.75 2.79 30 0.06 6.29 5.82

By gradient in toe is meant the average gradient measured betweendensity 0.1 and 1 above fog.

The above results obtained with a development activating solution ofvery simple composition, clearly show that it is possible in accordancewith the present invention to obtain a characteristic curve with shorttoe and high gamma.

EXAMPLE 2 A photographic material was prepared as described in example 1and divided into several aliquot strips. Under identical circumstances,the strips were exposed through a step wedge with constant 0.15 andtreated at 25C for increasing times in a development activating solutionof the following composition:

anhydrous sodium carbonate I00 g sodium hydroxide 5 g 100 gtriethanolamine sulphite 10 ml polyethylene glycol (molecular weightlitre 4000) l g potassium bromide 0.6 g l, l'-[ethylene-tris(oxyethylene )]bis (pyridinium p-tolusulphonate) 100 mgwater to make 1 litre (pH ll) to which one of the hydroxylaminecompounds listed in the table below was added in the amount given.

The developed strips were then fixed, washed and dried in the usual way.The results attained were as follows.

3 of hydroxylamine Deva lop- Fog Gamma Gradient compound added moat intoe per litre time(s.eo)

. 40 0.05 2. '74 '1 '70 10 g of '(na oa) .n so 1o 0.04 6.35 4.58

5.5 g or NH H.HCl 10 0.04 6.50 5.02

6.4 g of H50 NHOH.HC1 10 0.04 6.05 4.86 20 0.04 5.86 4.26

a g of HONH-CH-CH -c 0 04 5 60 5 56 O 2 I I O NHOH 0.04 6.05 4.96

11.8 g of HO5S-(CH2)5-NHOH 10 L004 5.60 5.96

The above results show the favourable effect of treating thehydroquin0ne-containing lith-type silver halide material with analkaline development activating solution in i the presence ofhydroxylamine or a N- monosubstituted hydroxylamine.

EXAMPLE 3 MATERIAL I MATERIAL 11 Material 11 was prepared in exactly thesame way as material I with the only difference that no hydroquinone waspresent in the first gelatin layer and that the gelatin antistress layercontained 1.6 g of hydroquinone per sq.m.

Both materials were exposed by the use of tungsten illumination througha step wedge and a grey contact screen.

After exposure the materials were developed for 30 sec. at 30C in thefollowing development activating solution:

sodium carbonate 100 boric acid 10 hydroxylamine sulphate l0 tetrasodiumsalt of EDTA 1 potassium bromide l polyethylene glycol (molecular weight4000) 1 water to make 1 The developed materials were fixed, washed anddried in the usual way.

The dot quality was evaluated in shadow (10 percent black dot coveragemiddle (50 percent black dot coverage) and highlight percent black dotcoverage) tone areas and given a quality from 0, which is excellent to 4which is extremely poor. Any dot quality above 3 is generally notacceptable.

1. Method of producing high-contrast images by exposure and developmentof a photographic lith-type sil-' ver halide material comprising asupport and a silver halide emulsion layer containing at least about 50mole percent of silver chloride, at least about 5 mole percent of silverbromide and from 0 to about 5 mole percent of silver iodide, wherein thesaid'photographic lith-type material incorporates hydroquinone asdeveloping agent, and development is effected by treatment of theexposed material with an alkaline development activator in the presenceof hydroxylamine or a salt thereof or of a N-monosubstitutedhydroxylamine or a salt thereof. 1

2. Method according to claim 1, wherein a hydrophilic colloidintermediate layer is arranged between the support and the silver halideemulsion layer.

3. Method according to claim 2, wherein the said-hydrophilic colloidintermediate layer has a weight comprised between about 2 g and about 10g of hydrophilic colloid per sq.m.

4. Method according to claim 1, wherein hydroquinone is present in thesaid hydrophilic colloid interntediate layer.

5. Method according to claim 1, wherein hydroquinone ispresent in ahydrophilic colloidcoating coated over the emulsion layer.

6. Method according to claim .1, wherein thehy droquinone is present inthe lith material in an amount comprised betweenabout 5 millimole andabout 25 millimole per sq.m.

7. Method according to claim 1, wherein the hydrox ylamine compound ispresent in the development activator.

8. Method according to claim 1 wherein the hydroxylamine usedcorresponds to the formula:

RNHOH wherein R is hydrogen, an alkyl group or an aryl group.

9. Method according to claim 7, wherein the hydroxylamine compound ispresent in the alkaline development activator in an amount comprisedbetween about 0.5 g and about 50 g per litre.

10. Method according to claim 1, wherein the pH of the alkalinedevelopment activator is at least 9.

11. Method according to claim 1, wherein the lithmaterial and/or thealkaline development activator comprises a polyoxyethylene compound.

12. Method according to claim 1, wherein the lithmaterial and/or thealkaline development activator comprises a N-vinyl-2-pyrrolidone polymeror copolymer.

13. Method according to claim 1 wherein after development the materialis fixed and washed.

14. Method according to claim 1, wherein after development the materialis treated with a stabilizing solution comprising an agent convertingnon-exposed silver halide in light-insensitive complexes.

15. Method according to claim 14, wherein said agent is potassium orammonium thiocyanate.

16. Method according to claim 14, wherein after treatment with thestabilizing solution the material is fixed and washed.

17. A photographic lith-type silver halide material comprising a supportand a silver halide emulsion layer containing at least about 50 molepercent of silver chloride, at least about 5 mole percent of silverbromide and from to about m olepercent of silver iodide,

wherein said material incorporates hydroquinone and hydroxylamine or asalt thereof or a N-monosubstituted hydroxylamine or a salt thereof.

18. A photographic material according to claim 17, wherein saidhydroxylamine compound corresponds to the formula:

RNHOH wherein R is hydrogen, an alkyl group or an aryl group.

19. A photographic material according to claim 17, wherein thehydroquinone is located in a hydrophilic colloid intermediate layerarranged between the support and the silver halide emulsion layer and/ora hydrophilic colloid layer coated over the silver halide emulsionlayer.

20. A photographic material according to claim 17, wherein thehydroxylamine compound is present in the said emulsion layer and/or ahydrophilic colloid layer in water-permeable. relationship therewith.

21. A photographic material according to claim 19, wherein saidintermediate layer has a weight comprised between about 2 g and about 10g of hydrophilic colloid per sq.m.

22. A photographic material according to claim 17, wherein thehydroquinone is present in the lithmaterial in an amount comprisedbetween about 5 millimole and about 25 millimole per sq.m.

23. A photographic material according to claim 17, wherein thehydroxylamine compound is present in the lith-material in an amountcomprised between about 50 mg and about I g per sq.m.

1. A METHOD OF PRODUCING HIGH-CONTRAST IMAGES BY EXPOSURE ANDDEVELOPMENT OF A PHOTOGRAPHIC LITH-TYPE SILVER HALIDE MATERIALCOMPRISING A SUPPORT AND A SILVER HALIDE EMULSION LAYER CONTAINING ATLEAST ABOUT 50 MOLE PERCENT OF SILVER CHLORIDE, AT LEAST ABOUT 5 MOLEPERCENT OF SILVER BROMIDE AND FROM 0 TO ABOUT 5 MOLE PERCENT OF SILVERIODIDE, WHEREIN THE SAID PHOTOGRAPHIC LITH-TYPE MATERIAL INCORPORATESHYDROQUINONE AS DEVELOPING AGENT, AND DEVELOPMENT IS EFFECTED BYTREATMENT OF THE EXPOSED MATERIAL WITH AN ALKALINE DEVELPMENT ACTIVATORIN THE PRESENCE OF HYDROXYLAMINE OR A SALT THEREOF OR OF AN-MONOSUBSTITUTED HYDROXYLAMINE OR A SALT THEREOF.
 2. Method accordingto claim 1, wherein a hydrophilic colloid intermediate layer is arrangedbetween the support and the silver halide emulsion layer.
 3. Methodaccording to claim 2, wherein the said hydrophilic colloid intermediatelayer has a weight comprised between about 2 g and about 10 g ofhydrophilic colloid per sq.m.
 4. Method according to claim 1, whereinhydroquinone is present in the said hydrophilic colloid intermediatelayer.
 5. Method according to claim 1, wherein hydroquinone is presentin a hydrophilic colloid coating coated over the emulsion layer. 6.Method according to claim 1, wherein the hydroquinone is present in thelith material in an amount comprised between about 5 millimole and about25 millimole per sq.m.
 7. Method according to claim 1, wherein thehydroxylamine compound is present in the development activator. 8.Method according to claim 1 wherein the hydroxylamine used correspondsto the formula: RNHOH wherein R is hydrogen, an alkyl group or an arylgroup.
 9. Method according to claim 7, wherein the hydroxylaminecompound is present in the alkaline development activator in an amountcomprised between about 0.5 g and about 50 g per litre.
 10. Methodaccording to claim 1, wherein the pH of the alkaline developmentactivator is at least
 9. 11. Method according to claim 1, wherein thelith-material and/or the alkaline development activator comprises apolyoxyethylene compound.
 12. Method according to claim 1, wherein thelith-material and/or the alkaline development activator comprises aN-vinyl-2-pyrrolidone polymer or copolymer.
 13. Method according toclaim 1, wherein after development the material is fixed and washed. 14.Method according to claim 1, wherein after development the material istreated with a stabilizing solution comprising an agent convertingnon-exposed silver halide in light-insensitive complexes.
 15. Methodaccording to claim 14, wherein said agent is potassium or ammoniumthiocyanate.
 16. Method according to claim 14, wherein after treatmentwith the stabilizing solution the material is fixed and washed.
 17. Aphotographic lith-type silver halide material comprising a support and asilver halide emulsion layer containing at least about 50 mole percentof silver chloride, at least about 5 mole percent of silver bromide andfrom 0 to about 5 mole percent of silver iodide, wherein said materialincorporates hydroquinone and hydroxylamine or a salt thereof or aN-monosubstituted hydroxylamine or a salt thereof.
 18. A photographicmaterial according to claim 17, wherein said hydroxylamine compoundcorresponds to the formula: RNHOH wherein R is hydrogen, an alkyl groupor an aryl group.
 19. A photographic material according to claim 17,wherein the hydroquinone is located in a hydrophilic colloidintermediate layer arranged between the support and the silver halideemulsion layer and/or a hydrophilic colloid layer coated over the silverhalide emulsion layer.
 20. A photographic material according to claim17, wherein the hydroxylamine compound is present in the said emulsionlayer and/or a hydrophilic colloid layer in water-permeable relationshiptherewith.
 21. A photographic material according to claim 19, whereinsaid intermediate layer Has a weight comprised between about 2 g andabout 10 g of hydrophilic colloid per sq.m.
 22. A photographic materialaccording to claim 17, wherein the hydroquinone is present in thelith-material in an amount comprised between about 5 millimole and about25 millimole per sq.m.
 23. A photographic material according to claim17, wherein the hydroxylamine compound is present in the lith-materialin an amount comprised between about 50 mg and about 1 g per sq.m.